Two power variants exist — 24V and 36V — each with its own diagram and parts list:
- 24V: Bill of Materials ·
- 36V: Bill of Materials ·
The pin mapping below is identical for both variants; only the power-rail voltages differ.
| ESP32-C6 Pin | TMC5160 Pin | Function |
|---|---|---|
| GPIO 1 | SCK | SPI Clock |
| GPIO 2 | SDI (MOSI) | SPI Data In |
| GPIO 3 | SDO (MISO) | SPI Data Out |
| GPIO 8 | CS | SPI Chip Select |
| GPIO 4 | EN | Enable (active low) |
| GPIO 5 | STEP | Step pulse |
| GPIO 6 | DIR | Direction |
| GPIO 7 | DIAG1 | StallGuard diagnostic output |
Substitute the variant's actual rail voltage (24V or 36V — see the BOM links above) wherever "PSU" appears below; the buck converter always steps down to 5V logic power regardless of variant.
The On/Off switch (#8) and the Emergency Stop (#10) are both in series on the positive rail, upstream of every load — see the wiring diagrams above for the full picture, including the fan supply, which differs between the variants.
| Connection | Details |
|---|---|
| PSU → On/Off switch → E-stop | Both in series on the positive rail, upstream of every load |
| E-stop → TMC5160 VM (HVIN) | Motor power |
| E-stop → Buck converter IN | Feeds the buck converter |
| Buck converter OUT (5 V) → ESP32-C6 | Logic power |
| PSU → Fan | See the variant wiring diagram — the fan supply is not the raw rail on every build |
| GND | Common ground between all boards |
The 36V build does not run everything from the incoming rail. It steps down twice:
| Connection | Details |
|---|---|
| Mains → C14 inlet → PSU L / N / ⏚ | Inside the PSU casing only — read the mains voltage warning first |
| PSU 36 V → XT60 → On/Off switch → E-stop | 18 AWG; the main supply line into the machine |
| 36 V → TMC5160 HVIN (8–60 V) | Motor power — the only 36 V load |
| 36 V → 36→24 V step-down IN | |
| 24 V → Fan | |
| 24 V → TMC5160 control-connector 24V pin | From the 24 V rail — never 36 V |
| 24 V → 5 V regulator IN; 5 V OUT → ESP32-C6 5 V | Logic power |
⚠️ Set the 36→24 V step-down before connecting anything to it. The module is adjustable and does not necessarily arrive at 24 V. Power it from 36 V with nothing connected to its output, measure the output with a multimeter, turn the trim pot until it reads 24.0 V, and only then wire the fan, the 5 V regulator and the TMC5160 24V pin. A mis-set step-down can put up to 36 V on parts rated for 24 V.
⚠️ TMC5160 24V pin: BIGTREETECH specifies that the control connector's 24V pin must not exceed 24 V whatever the motor supply is — exceeding it damages the driver. Only the HVIN terminal takes 36 V.
The Emergency Stop (#10) is normally-closed and cuts the whole rail — including logic power. Pressing it does not merely stop the motor: the ESP32-C6 loses its 5 V supply along with the TMC5160, so the controller powers down mid-stroke. This is the machine's only people-safety device; see the safety warning.
Because the controller reboots, the firmware comes back with the stepper's position counter at 0 while the carriage sits wherever it stopped. The stored calibration is restored but flagged unreferenced, and a run is refused until a Return Home re-establishes the reference against the UP hard stop. That is expected behaviour after every E-stop, not a fault.
Important: The display and TMC5160 share the SPI bus (GPIO 1, 2). The firmware manages chip-select lines (GPIO 8 for TMC, GPIO 14 for display) to avoid bus conflicts. The display CS is forced high before every StallGuard SPI read.